From another review (using water cooling): https://www.gamespot.com/articles/intel-core-i7-8700k-cpu-review-a-performance-leap-/1100-6453799/#TemperaturesAs stated earlier in the methodology, we used the NZXT Kraken X62; an all-in-one liquid CPU cooler with a dual-fan 280mm radiator. However, the 8700K still got pretty hot. At idle, the CPU sat at a mild 32 degrees Celsius and went up to 78 degrees Celsius under load during our runs of X264. With using the 5.0GHz overclock profile, it reached 86 degrees Celsius under load in X264, which is considered higher than desirable.

If you really prefer air coolers, you may want to consider beefier models such as the Noctua NH-D15 (though you may not like the "looks") or Thermalright Le Grand Macho. You may be able to hit ~4.8GHz, depending on the chip quality you would get.